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January 6, 2009

Broomstick Provides Space Elevator Breakthrough

by Sam Savage

A space elevator prototype, featuring a broomstick, has shaken up scientists' approach to the century-old idea.

In December, Age-Raymond Riise of the European Space Agency demonstrated the device for the space elevator project which could see a nearly 63,000 mile tether anchored to Earth as an "elevator" into space.

The idea, which was demonstrated at a recent space elevator conference, could solve many complicated hurdles, but still leaves much to be answered.

The space elevator concept was first championed by Russian scientist Konstantin Tsiolkovsky in 1895. The idea has captured the imagination of scientists ever since.

The concept relies on using the centrifugal force of Earths rotation. If the centrifugal force can be balanced with the Earths gravitational force, the tethers center of mass will be stuck in geostationary orbit, allowing it to be held firm permanently.

One of the long-standing issues facing the idea is how to power the "climber" that would take the cable up into space. Previous ideas include using laser or microwave power to propel the craft.

In December, Eurospaceward hosted the Second International Conference on Space Elevator and Tether Design to debate the elevator concept.

Mr. Riise, of the ESA, proposed sending power to the climber mechanically, by providing a precisely timed tug on the cable near its base.

To demonstrate his idea Riise used a broomstick to represent the cable. He then used an electric sander to vibrate the bottom of the broomstick.

At the broomstick's base he tied three brushes to represent the climber.

The vibration allowed the "climber" to move up the broomstick, against gravity.

Mr. Riise believes the idea could be effective if the vibrations on the cable can be smoothed out.

"It would be possible to make a suspension system that completely decouples the cabin where the passengers are," he said. "For them it would be a linear movement with very little disturbance."

The idea could simplify the problem of providing power to the climber, but many technical challenges still remain. One of the largest issues is the makeup of the cable.

Some believe the cable could be produced with carbon nanotubes, which would provide the mammoth strength-to-weight ratio needed for such a project. Others still debate as to whether a cable of that scale could be manufactured.

The space elevator would provide cheaper space missions, and would allow for the development of space-based energy solutions, making the project lucrative.

"From my point of view, the space elevator project is important because it enables a far more directly useful project - installation of large space solar power satellites around the Earth to provide continuous, cheap, CO2-neutral, environmentally friendly energy," said Benoit Michel of the Catholic University of Leuven.

"I firmly believe that the next century will have a large space-based industry and that industry will be the main energy provider for the whole mankind," he added.

Mr. Riise has been approached by lift companies to develop his idea for superscrapers. The simplicity of his idea seems more attractive than all other known ways of powering large lifts.

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Image Caption: Pound for pound, space elevator payloads would cost much less than rockets.